Software free of financial cost. For software that includes the source code, [open-source] is the best tag. Software can be either [gratis] or [open-source], or both. Only use this tag if "gratis" is a must-have requirement.

When I take a golf lesson the pro uses video to show me my swing. Whatever he uses allows slow motion, frame by frame jogging and the ability to draw lines on the video so I can compare my spine angle …

It has been a few years since this question was posted and I wanted to add another more recent option. Onshape is a 3D solid modeling application that runs in the browser and thus is cross platform. I …